Re: using another fs from an xfs

[Stephen Usher <steve@earth.ox.ac.uk>]

>
>Hi all,
>
>I was wondering what exactly you can and cannot do from within an xfs.
>For example, I'd still like to write a UNIXMODE fs, which would be based
>on TOSfs. Should I use a trick like ofake? Can I call GEMDOS through the
>kernel structure to open a file? I can always copy TOSfs and hack on it,
>but TOSfs still changes a lot, and it would duplicate a lot of code.
>It would be nice to be able to do this sort of thing, I keep dreaming
>of a zoo fs. (cd /z/a/newstuff.zoo;ls ;-)

To add to this.. can device drivers call other device drivers directly in
general in MiNT?

For example, if I were to write a new filesystem, could this call directly a
disk device driver which in turn would call a generic SCSI device driver?

Of course the bottom layer (the SCSI device driver) could be something else
like a generic ACSI device driver or generic IDE or generic floppy.. it
doesn't matter.

If so then this would allow MiNT to break free from the uni-process-biased
(ie they block MiNT whilst they go off and get the data) hard disk drivers we
have to use at the moment. All the GEMDOS and XBIOS functions for disks
would have to be emulated.. but that wouldn't be too much trouble.

Also, can xfs's put processes onto the IO queue until such time the data is
available? This would be a big performance gain if it could be done.

>
>Another question: Is it possible to use some sort of timer in an xfs to
>periodically sync(), without using a seperate update process? Can I just
>hook into a timer vector (vsync)?

I think there should be an Fsync() system call in MiNT which calls each of
the xfs's in turn calling their Fsync() functions. But that's just my
opinion.

>
>Bart.
>-------------------------------------------------------------------------------
>Bart Schuller    (NeXTmail OK) | What is a 're-mix?' "A total cheat"...
>schuller@dutiea.twi.tudelft.nl | ..."A gift"-- when it's Frankie...         TCH
>-------------------------------------------------------------------------------
>

I've waffled on too much already..

Steve

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